Downside Up, Upside down! Why You Need to Flip the Mic.
One of the questions that comes up from time of time when consulting with voice actors is “why do some people have their mic upside down?”. You’ll see mics positioned this way in every professional recording studio you go to, and in the home setups of many voice actors. The answer to this question has both historical and practical significance.
There was a period of time where tube microphones were common. The goal is to amplify the low signal from the mic capsule as close as possible to the source to keep the noise level low. Some tube powered microphones will even have their own power supply box that can rest at the foot of the mic stand, keeping the power close to the mic before running a longer cable to the mixer or preamp. The tubes inside the mic, however, heat up over time. So if you’re recording a vocalist during a long session, that warm air will cause the microphone’s diaphragm to expand- coloring the sound. The solution to this problem is simple! Hang the microphone upside down and let the heat rise away from the capsule. Tube microphones are still common today, especially in higher-end music studios. A great example of one is the Neumann U67. But Neumann developed a solid state alternative to their tube mics, and released the ubiquitous U87 as a tube-free version of the classic U67.
For voiceover work, tube microphones are rare and largely overkill. Most of the mics you'll be using at home don't have tubes: the U87, TLM 102, 103, Rode Nt1, Nt1A, Stellar X2, etc. So then why do so many studios and actors still opt for their mic to hamg upside down?